Hydraulic fitting



June 3, 1952 W HUME HYDRAULIC FITTING Filed Oct. 17, 1949 m NM w m mfl n 4 r a M w M a 3 a My w a B w y Patented June 3, 1952 HYDRAULIC FITTING William L. Hume, Los Angeles, Calif assignor to 'Douglas. Aircraft Company, Inc; Santa bliit hcs f- Application Qctober 1'7, 1949, Serial No. 121,775

f1 Claims. 1 his twent es. rel te o c p gv s an more pa t cu ar y o. c untin e ce f r s fittin Th co p i dev se o the pr nt v ntio n the br ade a t thereo wm ise an pres nt n an in e na .cx ne iss Wa u a o c ose rece vin th one end of the tube, which wall. surfac is enlar ed at h e n th reofto :form a ubstan ial to o dal Shoulder dapted to be engaged by an xt e tirtumferential bea s-previqusly .f rme ab u he tube lam nt the and r ceiv d w th n he yl ndric wallsur ac h a is held a a ns the 5110.111- der by compr ss on membe ev s the t b nd scen ed to be threaded c nn to the ans re eiving -1 .een :0. the tub T nd of the om essio memb adjacent t tub rec ivin means is. f rm d with a toroidal surface of substantial y t sam d met as h shoul which in tu n h s. su s antial h sam diameter h exte na /bead of he i t The ba al as it i en aged b t e n h Sh a d thetoroida rsur ace o th com e sio her is thus enclosed within a recess of substantially the same size and shape as the bead itself, and as the surface defining the recess are surfaces of rigid bodies, the tube is rigidly held s stilon i udi alm vem Although the. surfaces forming the recess enclosing the bead closely engage the surface of the bead and thus coact with the cylindrical wall surfacelclosely receiving the end of the tube to eficct ,a seal vof the jointure established, means are nevertheless provided for further sealing the clearance between the tube and the cylindrical wall surface. This means preferably comprises at least oneannular element of resilient and substantially non-compressible material fitted With-. in a circumferentially extending groove or channel formed in the cylindrical wall surface. The sealing element projects inwardly of said wall surface :to, sealingly engage the tube about the entire circumference thereof.

Although prior devices have been heretofore proposed for coupling tubes or the like in which the jointureeficcted is broughtabout by the restraining action of some means on a beaded section of the tube, these prior devices have not been entirely successful in use. These prior devices have either been on es in which the tube was outwardly expanded to form the bead after the end thereof was inserted within the device or ones which the surfaces between which the head was clamped were those of bodies or elemerits o fresilient material. Of the first mentioned group or class, these devices could not be used except Where special "forming" tools were available for expanding the tube. wall outwardly after the end of the tube was inserted into' the device. Such coupling devices obviously could not be readily bead'd'in the field and were difficult to use in close quartersfas in aircraft construction and maintenance; Furthermore; unless the tube was formed of'deads'oftimaterial it was a physical impossibility to fully expand the tube wall into the e larges iw'all surfaceintended to receivethe bead and the mechanical Vjoi'ntiire was consequently impaired by the relatively small bead eventually formed after the spring back of the wsn's eqnexpiinsed. These devices were also difiicult to' sealfpaiiticularly on .both sides of the jointure effectedby thedevice,

In the coupling device arise present. invention the bead can be formed during .rnanufactur'e of the tube, making unnecessary any beading operation during "the a's'ser i ibiybf the tube' in" fitting. Moreover, the upnn of the present invention can be used with relatively metals or other materials'iwhich can be p'rcvidediwith a bead during manufacture and which can not be readily beadedinthe field. Y

In the type of'previously proposed coupling devices where the members restraining movement of the bead were resilient ones which also served in most instances as gasket or sealing elements, the tube was'not rigidly or solidly anchored as in the, device of the present invention Where the surfaces engaging the opposite sides 'of the ;bead are those of rigid metallic 'rnernbers. A further difliculty inherent in these prior devices resulted from the fact that the bead restraining means and the sealing means wereone and the same, so that failure of this means produced not only a failure of theseaLbuft .raiiurgr the jcmture as well.

In thecoupling deviceof the present invention the rigid toroidal surfaces which restrain' the beaded wall portion ofithe tubelalso function as sealing means sothatifailure of the resilientsealing elementsdoes not result in a' complete failure of the seal. On the other hand, any injury or damage to the bead which mightinipair the sealing-actionoi the toroidal'fisur'faces does not affect the sealing action .Qfithe separate resilient elements.

The scaling elements of the present invention are disposed between the beadandithe adjacent end of the'tube sotha't there are my unsealed paths through which the fluids confined by the tube, even under relativelylhigh pressure, can

flow. As above mentioned, this was not true of the coupling devices which required outward expansion of the tube wall after the tube had been inserted into the fitting.

Other features and advantages of the present invention will be hereinafter apparent from the following description, particularly when taken in connection with the accompanying drawing in which the contours of the toroidal surfaces enclosing the beads have been slightly exaggerated to more clearlyillustrate the same.

In the accompanying drawing:

Fig. 1 is an elevational view, partly in section, of one embodiment of the present invention;

Fig. 2 is a longitudinal sectional view of a modified form of the coupling device of the present invention;

Fig. 3 is a sectional view similar to Fig. 2 but showing a still further modified form of the coupling device; and

'Fig. 4 is a section taken along line 44 of Fig. 1.

The coupling device of the present invention, referring now to the drawing, and more particularly to Fig. 1 thereof, illustrating one embodiment of the coupling device which comprises .a body member provided with a counter bore presenting an internal cylindrical wall surface H for closely receiving the adjacent ends of tubes [2 to be joined together in an end-to-end relation. The tubes l2 are each provided with an external circumferential bead I3 of a larger diameter than the tubes. The bead of each tube is spaced from the end thereof a distance slightly less than half the length of the cylindrical wall surface H and is formed prior to the assembly of each tube with the coupling device.

It is now preferred to form the bead on each tube by inserting the end of the latter in a die having a cylindrical wall surface of the same diameter as the cylindrical wall surface I I. The wall of the surface of the die is enlarged to form a toroidal surface into which the tube wall is upset or forced to form a bead. Beads formed by such an operation are far more uniform in size and shape than those formed by rolling a mandrel or the like about the inner surface of the tube.

Furthermore, the outer diameter of the tube wall during the bead forming operation will, of course, also be caused to conform to the diameter of the cylindrical surface of the die. This is particularly true of the sections of the tube wall adjacent the opposite sides of the bead. It follows that by closely maintaining the diameter of the counter bore of the body member a very close fit may be had between the tube and the bore of the body member.

The opposite ends of the cylindrical wall surface i I are enlarged to form a pair of oppositely facing, substantially toroidal shaped shoulders Id. The oppositely facing shoulders [4 are adapted to be engaged by the beads [3 of the tubes l2 when the latter are inserted within the opposite ends of the counter bore of the body member ID. As the bead of each tube is spaced from the end of the tube a distance less than half the length of the cylindrical wall, the beads l3 will be brought into engagement with the oppositely facing shoulders l4 without mutual interference of the end surfaces of the tubes. In other words, the end surfaces of the tubes I 2 will be held slightly apart after the beads are brought into engagement with the shoulders 14.

Each tube carries a compression member which may consist of an identical sleeve nut l5 which closely circumscribes the tube. Each nut, preferably, is formed with a plurality of toolengaging surfaces so that it may be turned by a suitable wrench or tool. The sleeve nuts l5 are formed with female threads adapted to be engaged with male threads formed about the 0pposite end portions of the body member ID. The engaged threads not only connect the sleeve nuts [5 to the opposite ends of the body member but also when the sleeve nuts are properly turned draw the latter toward the opposite ends of the body member.

The inner ends of the sleeve nuts l5 are each formed with toroidal surfaces I6 of substantially the same diameter as the toroidal shoulders I l formed by the enlarged wall portions of the cylindrical wall surface of the counter bore of the body member. The surfaces l6, as the sleeve nuts l5 are drawn inwardly of the opposite ends of the body member, are brought into compressive engagement with the exposed surfaces of the beads [3 to urge the beads against the shoulders I4 formed at the opposite ends of the body member l0. It will be seen that the toroidal surfaces l5 coact with the toroidal shoulders I4 to form internal recesses the walls of which engage the surfaces of the beads l3 and hold the beads, and consequently the tubes, against longitudinal movement.

As a stronger union or jointure, as well as a more rigid one, is had if the toroidal surfaces closely engage at least the surfaces of the root portions of the bead, that is, those surfaces of the bead disposed on opopsite sides of the bead which lie closely adjacent the normal or unexpanded wall sections of the tube, care should be taken to insure that the surfaces [4 and I6 are accurately machined or otherwise formed. As the beads will be accurately formed so that the same are substantially uniform in size and shape and as there is little difficulty in maintaining the proper contour of the shoulders l4 and surfaces [6, a very strong and rigid union can be had.

Although the cylindrical wall surface H presented by the counter bore of the body member In very closely receives the end of the tubes 12, it is now preferred to provide separate means for sealing the annular space between the outer wall of the tubes and the cylindrical wall surface of the body member. Although a number of sealing means can be effectively used here, it is now preferred to use conventional O-rings I! which are received within spaced circumferentially extending grooves I8 formed in the cylindrical wall surface II of the counter bore of the body memher In. These O-rings are preferably used with leather back-up washers l9 placed within each groove on opposite sides of the O-ring seated therein. As in conventional practice, the 0- rings are of a diameter slightlygreater than the depth of the grooves I8 and thus project inwardly of the cylindrical wall surface of the counter bore to sealingly engage each tube about the entire circumference thereof. The O-rings are formed of a resilient and substantially noncompressible material such as rubber and are effective to hold even relatively high pressures.

It should now be seen that the tubes I2 are rigidly anchored in an end-to-end relationship and that the jointure effected is sealed against the escape of fluids or the like carried by the tubes l2. This is so, for the only path of escape of a fluid is through the annular space intermediate-thetubes l2 and the cylindrical wall of well as by the walls of the recess enclosing the beads l3 and formed by the surfaces l4 and Hi, there is little ifany likelihood of fluid escaping or leaking from the union.

t mightbe pointed out here that even if one or both ofthe O-ri'ngs should fail in use the seal is not completely destroyed, for the very close fit of the tubes within the counter bore and the engagement of the surfaces i4 and 16 with the heads will prevent all but a very small seepage of the fluid.

In the embodiment ofthe invention shown in Fig. 2, the coupling there shown comprises a sleeve-like body member 2| having a bore 22' presenting a cylindrical wall surface which closely receives the end of the tube 23. The tube 23, as in the previously describedembodiment of the invention, is preformed through a die operation with a bead 24 which is adapted to engage a substantially toroidal shoulder 25 formed by an enlarged wall portion of the bore 22. The bead 24 is held in engagement with the shoulder 25 by a compression memher here shown as a sleeve nut 26 formed in this embodiment of the invention with male threads engageable with female threads of the body member 2|. The inner end of the sleeve nut 26 is formed with a toroidal surface 2-? of substantially the same diameter as the toroidal shoulder 25 of the body member. The surface 21 coacts with the shoulder 25 to restrain movement of the bead 24, for they coact together to provide a recess of substantially the same size and shape as the external surface of the bead 24.

In this embodiment of the invention the toroidal surface 2'! of the sleeve nut 26 compressively engages the bead 24 before the inner face 28 thereof engages the face 23 of the body member 2|. This insures that the bead 24 will be compressively engaged between the surface 2? and the shoulder 25 to provide arigid anchorage of the tube 23 before the sleeve seats against the body member.

As in the earlier described embodiment of the invention, an Oring 3|, together with the backup washers 32, is used to seal the annular space between the exterior wall surface of the tube 23 and the internal cylindrical wall surface presented by the bore 22. The O-ring is mounted in a groove '33 circumferentially formed in 'the bore 22 intermediate the ends thereof so that the O-ring will effectively prevent seepage of the fluid carried by the tube 23 to the left as viewed in-Fig. 2 and thence to atmosphere through-either the threaded connection or around the bead and thence to atmosphere'through the annular space between the sleeve nut ZB-and the tube 23.

Here again the tube is rigidly anchored against longitudinal movement by the surface 21 and the shoulder 25. As explained during the description of the embodiment of the present invention shown in Fig. 1, the surface 2l an'd the shoulder 25 shouldbe accurately formed so that they will-coact with the root portions of the bead to not only rigidly anchor the bead and thus the tube against movement but also coact to augment the seal produced by the O-ring 3|.

There isshown in Fig. 3 an embodiment of the coupling device of the present invention which can "be used if a swivel connection is desired. The embodiment of the invention illustrated in Fig. 3 also shows-the adaptation of the present invention to assemblies in which a tube 34" formed with a rightangled' bond is to be coupled to a device suchas a pump: or the like, the housing of whiehis-indicatedlby the reference character 35. In such: an installation the housing 35 may be formed-with abore 36 presenting an internal cylindrical? wall" surface for closely receiving the end of the tube provided with bead formed in the samemanner .as were the beads I3. The bore 3fi:i's:provided; with. an. enlarged wall means forming ,a toroidal shoulder 317' against which the previously formed bead 38 seats. The bead 38 is held in engagement with the shoulder 3'?! by a collar-or nut 39' closely sleeving the tube 34 and provided atits inner end with a substantially' toroidal surface 4| .of' substantially the same diameter as the shoulder 37. The sleeve nut 39 is formedwith male threads engageable with female threadsfonmed about the wall ofan enlarged portion of the bore 36 to the end that the sleeve nut may be (drawn toward the housing 35 tocompressively engage the bead 38 between the surface M and the shoulder 3.].

To prevent the bead 38 from being so compressively engaged between the surface 4| and the shoulder 31 that the swivel action desired can not be had, means are provided for so locating the toroidal surface 4| relative to the shoulder 37 that said bead will revolve within the recess formed between the surface! and the shoulder 31 upon the application of a preselected rotational force to thetube 34. This means, in the now preferred embodiment of this form of the invention, comprises an index means formed by an annular extension 42 of the sleeve nut 39. Theouter surface of the extension 42 is engageable with the surface 43 of the casing 35 and when brought into engagement with that surface willjlocate the surface 4| in such a position relative to the shoulder 31 that the bead 38, although held against free rotation within the recess, will nevertheless revolve therein upon the application of a preselected rotational force to the tube. It should be obvious that the relative disposition of the index means 42 and the surface 4 can be changed, to the end that the rotational force necessary to bring about rotation of the bead can be varied.

Althoughtheshoulder 3! and the toroidal surface 4;| will closely engage the head 38, particularly the root portions thereof, as above explained, separate means are here again employed to seal the annular space between the tube 34 and the cylindrical wall surface presented by the bore 3,6. The separate sealing means again preferably comprises an O-ring d4, together with suitable back-up washers 45 seated within a groove ,46 circumferentially formed in the bore 36 intermediate the ends thereof. As the tube, is mounted for'rotational movement about an axis coincident with the axis of the bore 36, it maybe desirable to use a pair of O-rings to accommodate any misalignment of the tube end received within the bore and the bore itself. In the preferred embodiment of the swivel form of 'thepresen't invention two O-rings 44, spaced as shown, are used.

"It should nowbe seen that in all embodiments oftheinvention illustratedthe anchorage of the tube is effected by compressively engaging the preformed bead of the tube between rigid surfaces coacting to form a recess of substantially the samesize-and shape as the-bead. The tube is thus rigidly or solidly anchored andthere is no danger of the tube moving longitudinally once the jointure is established.

The particular disposition of the separate sealing means or -rings very effectively seals each anchored tube and unlike previously proposed coupling devices, failure of the O-rings does not result in a complete destruction of the seal. This is so, for in each embodiment of the invention illustrated, the surfaces engaged about the beaded end of the tube will prevent a complete failure of the seal. Furthermore, any marring of the external surface of the bead or marring of the surfaces engaged about the bead does not impair the sealing action of the O-rings, so that the same care is not required in the assembly of the coupling device of the present invention as is required in the installation of the previously proposed devices in which the anchoring means also formed a part of the sealing means.

Although the now preferred embodiments of the present invention have been shown and described herein, it is to be understood that the invention is not to be limited thereto, for it is susceptible to changes in form and detail within the scope of' the appended claims.

I claim:

1. A device of the type described, comprising: means presenting an inner cylindrical wall surface closely receiving the end portion of at least one tube having spaced from the inner end thereof, an external, annular bead having a toroidal exterior surface angularly intersecting the tube wall in two longitudinally .spaced and opposed root-circles to define abutment shoulders; the inner cylindrical Wall surface of said receiving means being radially enlarged adjacent the one end thereof in the form of a rigid toroidal abutment having a larger outside diameter, a smaller radius of curvature and. a greater degree of inflection than the bead, with the toroidal surface of said abutment disposed radially outwardly of, and concentric with, the adja cent portion of the outer toroidal surface of said bead; a tube anchoring longitudinal compression member circumscribing said tube 1ongitudinally outwardly of said bead and having an inner cylindrical wall surface radially enlarged adjacent said bead in the form of a complementary rigid toroidal abutment having the same radius of curvature as the first said abutment and with the toroidal surface thereof disposed radially outwardly of, and concentric with, the adjacent outer toroidal surface of said bead; and means for connecting said anchoring member with, and for drawing the same toward. said receiving means to directly apply solely to the abutment shoulders at the root circles of said outwardly extending tube-wall intersecting exterior bead surface tangential forces having equal and opposite longitudinal components which are concentrated on said shoulders; thereby to longitudinally couple said tube in said receiving means clampingly and to provide a sectionally crescent shaped clearance chamber in the form of a lune of revolution lying radially between said toroidal abutment surfaces and the exterior toroidal surface of said bead to accommodate radial outward movement of said bead under longitudinal contraction and expansion of said tube caused by thermal forces and by overtightening of said anchoring means.

2. A device of the type described, comprising: means presenting an inner cylindrical Wall surface closely receiving the end portion of at least one tube having spaced from the inner end thereof, an external, annular bead having a toroidal exterior surface angularly intersecting the tube wall in two longitudinally spaced and opposed root-circles to define abutment shoulders; the inner cylindrical wall surface of said receiving means being radially enlarged adjacent the one end thereof in the form of a rigid toroidal abutment having a larger outside diameter, a smaller radius of curvature and a greater degree of inflection than the bead, with the toroidal surface of said abutment disposed radially outwardly of, and concentric with, the adjacent portion of the outer toroidal surface of said bead; said cylindrical wall having an annular, relatively broad and shallow, groove therein located intermediate said bead and the adjacent inner end of the tube and adapted to receive sealing means; a relatively resilient, non-compressibly deformable sealing member mounted annularly in said groove and flanked on each longitudinal side by a relatively non-resilient, compressibly deformable, rectangular section sealing member, said members projecting radially inwardly to sealingly engage the circumference of the tube and being compressed radially by the receiving member and the tube end to provide a single, cylindrical, fiat surface contact between the sealing members and the tube wall, thereby to distribute the sealing effect of said receiving members and tube end together over a relatively wide area as compared to the groove depth and with a concentrated sealing force; a tube-anchoring member circumscribing said tube longitudinally outwardly of said bead and having an inner cylindrical wall surface radially enlarged adjacent said bead in the form of a complementary, rigid, toroidal abutment having the same radius of curvature as the first said abutment and with the toroidal surface thereof disposed radially outwardly of, and concentric with, the adjacent outer toroidal surface of said bead; and means for connecting said anchoring member with, and for drawing the same toward, said receiving means to apply all longitudinal coupling forces substantially tangentially to the abutment shoulders only of the bead, so that the bead takes all longitudinal coupling and clamping forces, relieving the seal from all longitudinal coupling and clamping forces; thereby to enable the sealmg members to lie flat in their groove and to maintain their planar sealing contact with the tube end laterally untilted, thereby to enhance the sealing effect of said sealing members.

3. A device of the type described, comprising: means presenting an inner cylindrical wall surface closely receiving the end portion of at least one tube having spaced from the inner end thereof, an external, annular bead having a toroidal exterior surface angularly intersecting the tube Wall in two longitudinally spaced and opposed root-circles to define abutment shoulders; the inner cylindrical wall surface of said receiving means being radially enlarged near the one end thereof in the form of a rigid annular abutment, the inner portion of which has a greater degree of inflection than the bead and the outer portion of which lies spaced radially outward of said bead to provide with said inner portion an annular clearance around said bead; a tube anchoring longitudinal compression member circumscribing said tube longitudinally outwardly of said bead and having an inner cylindrical wall surface radially enlarged adjacent said bead in the form of a rigid annular abutment extending outwardly with a greater degree of inflection than said bead and cooperating with said first abutment to provide an amiular clearance chamber about the exterior toroidal surface of said bead to accommodate radial outward movement of said bead; said abutments contacting the abutment shoulders of said bead only at said opposed root circles to define two axially spaced, concentric, annular lines of contact to hold said tube in accurate axial alignment with said receiving means and said compression member; means for connecting said anchoring member with, and for drawing same toward, said receiving means to produce said line contact between said abutments and said abutment shoulders; and annular resilent sealing means mounted in said receiving means and adapted to engage the external surface of said tube in sealing relation; the accurate alignment of said tube relieving said sealing means of mechanical loads, thereby to enhance its sealing efiect.

4. The device as claimed in claim 3 and, in addition thereto; index means carried by said 10 anchoring means and engageable with said receiving means for so locating said abutments relative to said abutment shoulders that said bead is free to rotate about its axis upon the application of 'a relatively light rotational force to said tube.

WILLIAM L. HUME.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 188,213 Weiss Mar. 6, 1877 1,533,886 Mueller et a1. Apr. 14, 1925 1,817,854 Sorensen Aug. 4, 1931 1,961,453 Quarnstrom June 5, 1934 2,377,196 Walley May 29, 1945 2,459,956 Muller Jan. 25, 1949 2,460,032 Risley Jan. 25, 1949 2,535,694 Payne Dec. 26, 1950 

